Original Arri 16mm ST matte box vs modern 15mm rod matte box?

[Gillian Donaldson-Selby]

I'm having my Arri 16 ST CLA'd with a few upgrades and was wondering which matte box / sunshade would work best for the camera in the future - the original matte box or a modern matte box on rails. I would like to keep weight and size down as much as possible (to hump it across peat bogs) and plan on using prime lenses at this time. I did some experimenting with a standard 15mm rod-based matte box, and it seems that the centre of the matte box is too high for the camera. On the other hand, I wonder how heavy (and potentially cumbersome) the original matte box is. Any thoughts much appreciated!